Monday, 25 February 2013

Norton P86 750 Challenge - Norton's Last Gasp

When we think of the death of the British
motorcycle industry in the 1970s, we generally recall the final generation of
cantankerous, leaky, vibrating, old fashioned crock-pots being foisted onto an
increasingly apathetic market. These were conservative and under-engineered
machines that harkened back to an earlier era of motorcycle design (and lax
quality control). With the advent of oil tight, reliable, well built, and
fine-riding Japanese motorcycles (with – gasp – electric starters), the writing was on the wall for most of the British
marques. Some made a last-ditch attempt to stave off failure by hurriedly
cobbling together something that might be competitive against the Japanese
onslaught.

Norton’s last-ditch effort was the
remarkable, but virtually forgotten, P86 “Challenge” prototype built around a
liquid-cooled, double overhead cam twin designed in partnership with famed
engine builder Cosworth. It would prove to be too little, too late, and the
entire project would become mired by traditional British engineering
conservatism and a general lack of funding as the venerated Norton brand
wheezed its final breaths.

Let’s take a step back to the early 1970s.
Norton was still capitalizing on the success of their Commando platform, which
began as a quick prototype built around the antiquated 750 Atlas motor in a
rubber-damped frame that isolated the rider from the (stupendous) vibrations of
the big parallel twin. Even in the 1960s the Norton twin was considered an
obsolete design, a creaky old motor that dated back to 1948 (and that wasn’t
particularly groundbreaking back then, either). That original design was a
497cc mill, and subsequent years and attempts to remain competitive had packed
on the cubes to bring the engine up to 745cc and finally 828cc. More
displacement meant more power, but also more vibration from the paired
cylinders and an increasingly stressed design that was overstretching the
original design specs by a fair margin. The final 828cc versions actually
detuned the power slightly to improve reliability - they made the same power as
the earlier 745cc motors.

Image Source
The famous John Player Norton monocoque chassis, circa 1973, built around the antiquated pre-unit twin.

While sonorous and torquey, and potentially
reliable if setup and maintained correctly, the Norton pre-unit twin was a
dinosaur that was far from the cutting edge of motorcycle design. It was
particularly disadvantaged in racing by the 1970s. Japanese competition was
becoming fierce in production classes. Norton racers were down on power and had
significant reliability problems. Their chassis designs were reasonably
competitive and sometimes quite innovative - the famous John Player Norton
monocoque designs achieved some success and had some impressively
forward-thinking frame design. Problem was underneath all the trick bits was
that tired old OHV, air-cooled, two valve per cylinder twin and its fragile
pre-unit gearbox, clattering out 70 odd horsepower while the competition was
getting into triple-digit power figures. Something more modern and more
competitive was needed, for both the street and the track.

Norton approached Cosworth in 1973 to help
build a modern powerplant that would serve as a new generation of motor for
future street machines, as well as provide a competitive base for racing.
They’d also have a proper motor to go along with their advanced monocque race
chassis. Cosworth, in addition to being as British as polo injuries, was doing
quite well in Formula 1 with its excellent Double Four Valve (DFV) V8 which had
been developed in 1966. The idea was to use 1/4 of a DFV, which coincidentally
would equal 750cc using the DFV’s bore and stroke, arranged as a parallel twin.
It would be liquid cooled, have a modern four-valve head, dual overhead cams,
and Cosworth-style flat combustion chambers. The design brief called for
65-75hp in street spec, and at least 100 hp in race tune. As the DFV made
around 400-450hp from 2993cc, this seemed like a reasonable goal.

The boys from Northampton set to work
developing an engine for what would be dubbed prototype 86, or P86. It was a
liquid cooled parallel twin with a 85.6mm x 64.8mm bore and stroke, same as the
DFV, giving 746cc. Dual overhead cams were driven off a single gear nestled
between the two cams on the right side, similar to the DFV except that an
automotive-style toothed timing belt drove the assembly. The DFV used a gear
train to turn the cams, but this was noisy and required lubrication – the
timing belt was a simple solution to both problems. A modern four-valve per
cylinder head with DFV dimensions (shallow pent roof with 32 degree included
valve angle, flat top pistons, large valve surface, wide ports) promised good
breathing and combustion, the hallmark of Cosworth F1 motors which had hit upon
the ideal formula for a modern flat combustion chamber design. Indeed, above
the crankshafts there wasn’t much to distinguish the P86 from the DFV – they
shared the same combustion chamber and head designs, and even used the exact
same pistons and con-rods. There were literally Formula 1 parts inside the
P86.

Norton, being Norton, wouldn’t leave the
Cosworth team to its own devices and stipulated several anachronistic design
features that would prove to hamper the design significantly. One such
requirement was that the twin must be capable of running through a single
source of carburetion to make passing emissions testing easier, which
necessitated the “traditional” firing sequence. That meant a time-honoured
360-degree interval, with the pistons rising and falling as a pair like God,
the Queen and Bert Hopwood intended. Which meant the usual stupendous amount of
vibration you get from a big British twin shaking itself to pieces.

But of course vibration was not acceptable
in a modern design, so rather than attempt to change the firing interval and
risk making it harder to tune for increasingly strict emissions laws, a dual
counter balancer system was developed. Problem solved. Except the counter
balancers needed to be 20 pounds. You also need a massive, heavy flywheel to maintain
tractability (and hold an idle) on a big twin, and Norton insisted on sticking
it between the crankpins in the centre of the engine, just like they and
everyone else in Britain had always done - which precluded the possibility of a
strong centre main bearing. Famed technical writer Kevin Cameron wrote a detailed technical analysis of the P86 in 1980 and noted that the engine weighed 195
lbs, with seventy-five pounds of that being
rotating mass inside the engine. That’s a lot of inertia to overcome,
especially for something that is supposedly a racing motor.

The DFV was a fuel-injected design, and had
downdraught ports that took advantage of the perfectly metered flow that fuel
injection offers. The P86 had a similar port design, but it was fed by
antiquated Amal carburettors – the ports needed to be level at their entry to
keep the carburettor floats on an even keel, and then turned down sharply to
meet the valves. Both the port design and the odd angle conspired against power
and hampered the fuel delivery. And Norton wanted to stick a single carb on the
street version!

Tradition wins over modern engineering, in
customarily British fashion. We’ve always done it this way, old boy, so how dare you suggest those Japs have a better idea. My family has been working
for Nortrumpetbizzalocette for three generations; I think I ought to know a
thing or two about building motorcycles.

Norton wasn’t the only one complicating the
process - Cosworth made things difficult as well. As per their practice with
their F1 engines, Norton engineers and mechanics were forbidden from opening or
adjusting anything inside the motor. Any repairs, maintenance or modifications
were to be carried out by Cosworth techs alone. Having two sets of engineers,
who don’t share information, working on a single project is a sure fire way to
get stymied in a real hurry.

The end result was a motor that was
certainly better than the old pre-unit twin, but far behind expectations. In
top racing tune with twin carburettors they achieved about 90 hp on the test
bench in peaky, breathless fashion - not what they had been hoping for. The
massive amount of rotating weight inside the engine hindered response, while
the massive weight of the motor itself meant it was never going to be as light
as the Japanese competition. The lack of a centre main bearing limited
potential rpms and increased flexibility of the crank. The belt driven timing
was inaccurate and the belts themselves fragile. During his teardown of the P86
Kevin Cameron noted several odd design shortcomings, like a wholly inadequate
crankcase ventilation system that was surely robbing valuable horsepower.

Regardless of the shortcomings the project
plugged ahead. A special chassis was developed that was virtually frameless,
using the engine as a stressed member with vestigial supports for the subframe
and steering head. The new bike was raced publicly for the first time at Brands
Hatch in 1975… Well, to say it was “raced” is being generous. They showed up
and promptly crashed into a multi-bike pileup that occurred on the first lap.
This was the P86’s introduction to the public, after repeated delays, so
despite the fact the accident wasn’t their fault it did nothing to aid the
reputation of the supposed saviour of the British industry. Subsequent outings
on the track had disappointing results, with the P86 “750 Challenge” falling
far behind the much more powerful opposition. Some attempts were made at
modifying the chassis to improve handling but it wasn’t enough to make up for
the significant power deficit.

Meanwhile, Norton was in dire financial
straits and money to continue the project simply didn’t exist. There had never
been enough funds to maintain the project in the first place. The company had
been operating on borrowed time for years, and the P86 project had been in
constant flux. Norton could barely keep solvent in the early 70s, particularly
after the Combat engine disaster hurt their bottom line and their reputation,
and by 1975 the end was near. Famed racer Phil Read offered to take over
development, but upon further diligence he promptly withdrew his offer and
declared the P86 was not going to be a winner without serious changes.
Meanwhile Cosworth was committed to Formula 1 efforts and could not devote a
great deal of energy towards a dying, chronically underfunded project like the
P86. Circumstances were conspiring against the success of the P86.

After months of labour difficulties and
slumping sales, parent company Norton Villiers Triumph was split up in 1976.
The main factories were closed and production of spare parts was taken over by
an offshoot company dubbed NVT Engineering, who would also continue production
of the Commando using the existing parts stock in 1977-78. The racing and test
departments were disbanded, the prototypes gathering dust were sold off. The
P86 was no more, and the existing bikes and spare engines (about 30 in total)
disappeared into the ether.

Well, most of them disappeared. Remarkably,
the P86 would make a comeback ten years later at the 1986 Daytona Battle of the
Twins as the Quantel, a trick machine powered by a “Cosworth” engine… which
happened to be the old P86 engine - reworked, fuel injected, and punched out to
823cc. The Quantel would take second place in 1986, with a win in 1988, and would achieve some success in European BOTT venues as well. It
seemed that with Norton out of the way and a few more years of development, the
P86 could be made into a competitive racing platform. The story goes that when United Engineering Industries took a controlling interest in Cosworth in 1984, new chairman Robert Graves (founder of the Quantel media company in the UK) was being given a tour of the facilities by Keith Duckworth (the "worth" in "Cosworth"). Graves spotted the P86 engine sitting in a corner, and asked Duckworth about it. Duckworth declared "You're looking at the only engine we have built that has never won a race.". Apparently Graves saw this as a good challenge and promptly took the old engine, sunk another 100 000 pounds sterling into further development, hired John Surtees to help tune it, and made it competitive. Good press for Cosworth,
not much help to Norton (who began building Wankel-rotary powered motorcycles
from 1983 onward).

The P86 “Challenge” faded into obscurity
after the collapse of Norton Villiers Triumph in 1976 and today remains an
interesting footnote in the history of the British motorcycle industry. Here
was a genuine attempt at modernity that had high hopes tied to it. Some speculate
that if the P86 had been developed earlier, when the British were still at the
top of their game, the British motorcycle industry could have turned out very
different… Could, would, should – didn’t. It was too little, too late, and the
project was hampered by the traditional “we’ve always done it this way” attitudes and a severe lack of cash flow. Thus the British
industry collapsed under its own hubris, Norton was broken up, and the P86
became a dusty relic of “what could have been”.